This invention relates generally to fluid pressure regulation and more particularly to pulsation dampers for absorbing pressure pulsations and pressure surges in a fluid handling system.
Air operated diaphragm pumps and other low pressure pumps generate fluid discharge pressure pulsations which correspond to changes in direction of movement of the diaphragm in the pump. In some applications, such pulsations are objectionable because they cause inconsistent flow, hydraulic system shock, and potentially can damage associated fluid handling equipment.
Pulsation dampers are used to reduce the magnitude of, or to eliminate entirely, the pressure pulsations described. These damp hydraulic system pressure pulsations and smooth out flow variations resulting therefrom. Pressure pulsations are absorbed in the pulsation damper by compression of a fluid volume within the damper. Most dampers employ a diaphragm to separate the compressible damping fluid from the working fluid in the pumped system. This permits damping to be performed without contaminating the pump fluid.
The size and type of pump in the system determines the performance requirements for the pulsation damper in the system. The performance of the pulsation damper is related to the volume of compressible fluid in the chamber behind the diaphragm and the amount of fluid volume required to compensate for fluid output loss.
In a so-called "precharge" type pulsation damper, a precharge of compressible fluid, hereinafter air, is provided to the air chamber behind the diaphragm. The air chamber precharge is typically on the order of 80 percent of the working system pressure. This precharge is commonly manually provided and manually adjusted when system pressures are changed.
Another type of pulsation damper provides automatic pressure compensation so that the air pressure behind the diaphragm is maintained in its optimal range automatically in response to changes in the operating pressure range of the system.
In operation, pulsation dampers absorb the energy of pressure pulses by compression of the air volume behind the diaphragm. That energy is returned to the system by expansion of the air in response to pressure drops in the system. These compressions and expansions are accompanied by equivalent increases and decreases in the volume of the working fluid portion of the pulsation damper. Typically, self-compensating or automatic pulsation dampers adjust air volume and pressure by admitting or releasing air in response to pressure changes in the working system. These adjustments occur whenever the displacement of the diaphragm exceeds some limit as determined by the pumping conditions. Usually, a rod which is connected to the diaphragm, reciprocates in response to movements of the diaphragm and operates a compressed air inlet or exhaust valve. Since these rods penetrate the wall of the air chamber, they require lip seals to prevent unintended leakage of air from the chamber. These seals as well as the mating portion of the reciprocating rod are subject to wear and may require frequent maintenance. Ultimately, such maintenance requirements reduce the productivity of the system in which the pulsation damper is used.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.